Composite Thread and Obtained Textile

ABSTRACT

The invention relates to a composite thread ( 18 ), comprising a core ( 16 ) and a shell ( 17 ). The core ( 16 ) is produced from at least one thread of one or more metallic materials with biocidal properties. The shell ( 17 ) is made from one or more textile fibres directly covering all or part of the core ( 16 ).

The invention relates to a composite yarn. The invention also relates to a textile obtained with the composite yarn, used alone or in combination with other textile materials. The invention also relates to an article of clothing or of packaging made from this composite yarn.

In general, one function of a textile is as a protective covering for packaging, covering and protecting living or inert materials against the main factors harmful to their safety. Textiles provide protection against biological attack, such as by bacteria, fungi, yeasts, viruses, allergens or algae, against chemical attack, such as by gases, fumes or dust, against physical attack, such as by irradiation, hot or cold air or moisture and against mechanical attack, such as by friction, impacts, bites and cuts. A yarn is a basic constituent of a textile and has characteristics of flexibility, of fineness and of a long length relative to its diameter.

The therapeutic properties of certain metals have been widely recognized for a long time. Copper, zinc and silver in metal form are highly biocidal or germicidal, through action against microorganisms such as bacteria, yeasts and fungi, and algicidal through action against algae, according to a specific mechanism called “oligodynamic effect”. These metals are virtually insoluble in water. The few ions produced penetrate into the cells of the microorganisms or of the algae and act by complexation of the metal ions formed (Cu²⁺ for copper, Zn²⁺ for zinc, Ag⁺ for silver) on the thiol (—SH), carboxylic (—COOH), phosphate (—PO₄H₂), hydroxyl (—OH), amine (—NH₂), imidazole or indole groups of the proteins and on the bases of the nucleic acids of the RNAs in the cell nucleus. The growth of these microorganisms or of these algae is inhibited by biocidal action. The bacterial cells are in a state of bacteriostasis, since they are rendered sterile and can no longer divide. Consequently, the bacterial population no longer multiplies.

PRIOR ART

According to the literature, the antibacterial activity of copper is limited to Staphylococcus and Streptococcus (Gram⁺). Copper-based compounds, and in particular copper sulfate, are especially endowed with antifungal properties. Copper is active on fungi such as Trichophyton interdigitale or Trichophyton gypseum. Copper is inactive against other filamentous fungi such as Aspergillus niger. The antibacterial activity is greater on Gram⁻ bacteria than Gram⁺ bacteria.

In order to combat the microbiological risks, one technique consists in enriching the textiles with active agents. These agents are added to the fibers, to the yarns and/or to the textile. To date, various antimicrobial, antibacterial and antifungal agents exist and are widely used in this field.

First of all, minerals or zeolites, for example calcium or alkali aluminosilicates or tectosilicates, are combined with metals, such as principally copper, silver and zinc. They are incorporated into fibers obtained by a melt route. By way of example, mention will be made of ceramic based on silver and zirconium phosphate, marketed under the name AlphaSan® RC 5000.

These agents are also added at the surface of several fibers. These are, for example, a nylon-6,6 polyamide filament, known as X-static™, sold by the company Noble Fiber Technologie. These mineral treatments are suitable for textiles which have high melting points, greater than 250° C., such as polyamides or polyesters.

Next, chemical molecules, such as triclosan (Irgasan® from the company Ciba Specialty Chemicals), constitute agents with a broad antibacterial and antimicrobial spectrum. Triclosan can only be integrated into materials with a melting point below 215° C.

Finally, chitosan is a natural polymer derived from chitin which is used in health and agricultural applications, and also as a dyeing auxiliary for fabrics. It also cleans and clarifies swimming pool water, by eliminating the algae and other impurities.

However, these processes have the problem of the amount of antimicrobial agents to be incorporated in order to obtain probative results without modifying the characteristics of the fiber. In fact, zeolites are minerals that make the yarn brittle. Furthermore, the thermal stresses can also modify, or even destroy, the chemical characteristics of the antimicrobial agents, such as triclosan. In addition, these antimicrobial agents can also be incorporated after extrusion, during sizing of the yarns or in processes for coating and/or dyeing the yarns. However, the permanence of the metal and of the metal ions over time is only very random. The size will undergo friction and its resistance in an aqueous medium remains limited. These treatments with zeolites, gaseous metal deposits or coating, or impregnation with triclosan or chitosan, are labile and can be extracted with solvents, with laundry detergent, with sweat or with other chemical dyeing or bleaching agents, or through the temperature. This means that the effectiveness of the antimicrobial agents will decrease and disappear as the textile is used.

In order to be active against the microorganisms which exist on the surface of the fibers, a part of the active ingredient incorporated into the polymer must be located on the surface. The depletion of active ingredient due to the dyeing treatment, to abrasion or to extraction by sweat or by maintenance products must be compensated for by a slow migration through the filament or fiber to the surface. The concentration by mass of active ingredient, its distribution, its mobility in the polymer and the diameter of the filament or the fiber are therefore important parameters.

While maintaining a high effectiveness, the textiles obtained with sizing or finishing product exhibit cleaning better resistance than the textiles which have been subjected to simple deposition without binder. However, the presence of binder will modify the surface properties of the fibers, the bonding of the fibers to one another and, consequently, the properties of the fabrics (flexibility, handle and appearance) and will partly mask the effectiveness of the biocidal molecules. The durability of these treatments depends on many factors, the main one of which is strength of attachment of the active ingredient to the surface of fibers with respect to the dyeing conditions, to abrasion and to washing.

DISCLOSURE OF THE INVENTION

The main problem that the invention is intended to solve is that of producing a yarn that prevents the development of bacteria, fungi, algae or even other living elements. A second problem is that of keeping the “textile” handle for a yarn with bacteriostatic properties. A third problem consists in making the bacteriostatic properties of a yarn long-lasting, without alterations over time and independently of the conditions under which the textile is used. A fourth problem is that of preventing the formation of unpleasant odors, and of allergies, by developing a new type of yarn for a textile. A fifth problem consists in producing a yarn that can be finished without any specific precautions, dyeing, printing, and the like. A sixth problem is that of preventing the formation of static electricity in a textile through the addition of a specific yarn. Finally, a last problem is that of producing a textile article or an article of clothing, comprising at least one yarn with biocidal properties.

In accordance with the present invention, a composite yarn comprising a core and a sheath, characterized in that the core is made from at least one continuous yarn of one or more metallic materials with biocidal properties and in that the sheath is made from one or more textile fibers directly covering all or part of the core.

In other words, the core provides the biocidal properties and the sheath provides the characteristics of yarns conventionally used in the textile field. The term “biocidal” is understood to mean properties which refer to the European Biocide Guidelines 98-8. The expression “yarn of one or more metallic materials” is also intended to mean sections of continuous yarn, which may be calibrated or isotropic and spun together with a fiber tape. The expression “one or more textile fibers” is also intended to mean yarns or a continuous filament.

The yarn will thus have bacteriostatic, fungistatic and/or algicidal properties, with slow and controlled diffusion. It is therefore a yarn which, by virtue of its composition, prevents the development of elements that are potentially pathogenic for living beings. The yarn and the embodiments thereof it are no longer a source of contamination for materials with which they come into contact. The metal ions released by the core of the yarn penetrate and complex with the ribonucleic acids and the proteins of the microorganisms, thus blocking any multiplication. The presence and the low solubility of this metallic core in a liquid medium confer on it an extreme longevity, related to the fact that it is permanently present in the yarn. The sheath will provide the properties usually known for the textile yarns of the prior art.

By virtue of its characteristics, this type of yarn is used in the field of human and animal hygiene, food safety, the medical environment, the agricultural environment, and the filtration of aqueous and gaseous media. The yarn is suitable for possible use according to all the techniques used in the textile, winding, dressmaking, weaving, knitting, braiding, embroidery or napping field, and the like.

In a specific embodiment, the yarn(s) of the core can be plated (coated by electrolysis) with one or more metal materials with biocidal properties. This embodiment makes it possible to obtain a composite yarn, only the metallic surface of which has the desired biocidal properties. In another variant, this same embodiment relates to a composite yarn of a first metallic material with the desired biocidal properties which is plated using a second metallic material with other desired biocidal properties. The presence of two materials, copper and silver, prevents any oxidation of the two metals. On the yarn, there are no black traces (in the case of silver) or bluish traces (in the case of copper).

Very preferably, in order to promote the hold of the textile yarns or fibers on the core of the yarn, the core can have an apparent surface with a structure which forms points of attachment for the textile fiber(s) of the sheath. All the types of structuring of a metallic yarn are possible. Thus, the core has a geometrical structure, such as, for example, a strand, a strip, a star, a scale, a filamentous structure or any other shapes, which facilitate the attachment and the grip of the textile. Depending on the type of fibers used for the sheath, the metal core may be striated or peened, or undergo any type of treatment, in order to facilitate the attachment of the sheath. Similarly, a porous nonplanar structure may be produced in order to trap microbubbles of air, the aim of which being to increase the exchange surface areas and to improve the thermoregulatory characteristics of the yarn.

If the intention is to influence the microbial and antistatic characteristics of the core, its geometrical structure may be adjusted. In fact, depending on the type of migration desired, it will be possible, by virtue of the geometrical structure used for the core, to affect either the degree of solubility or the oligodynamic effect. This effect lies in the mass/area ratio of the core and the mass/area ratio of the yarn. If the desire is to have a greater effect on a given yarn, with an identical mass for the core, a strip is then preferred in place of a strand. A greater chemical exchange surface area will thus be obtained for an equivalent mass. This phenomenon can be further increased by producing a nonplanar, granular, striated or scaly surface. These various factors make it possible to regulate the levels of migration so as to comply with the regulations for individual and overall migration required for approval for contact with food products.

According to the desired biocidal activity, the metallic material(s) with biocidal properties can be preferably chosen, as individual metals or as an alloy, from the group comprising zinc, silver, tin, copper, gold and nickel. Through this choice of metallic materials, the targeting of the bacteria and other pathogenic elements to be destroyed results in a broad-spectrum effectiveness or, conversely, an effectiveness with a precisely targeted specific action. For a food-related application, the objective of which will be to verify pathogenic colonies, such as Listeria, Salmonella, Escherichia coli, Staphylococcus aureus, etc. the mixtures will be predominantly composed of zinc and silver, the presence of copper being less essential. On the other hand, if the yarn is intended for the prevention of odors in a shoe insole, the fungistatic function will be more predominant and, in this case, the proportion of copper will be greater.

The presence of the metallic core, which is an electrically conducting material, in the yarn of the present invention will therefore be sufficient to dissipate static electricity charges. The presence of a metallic core, at the core of a composite yarn, gives the latter a cutting resistance function.

Depending on the textile desired at the end, the textile fiber(s) of the sheath can be chosen, alone or as a mixture, from the group comprising fibers of natural, artificial and synthetic origin. In a first case, the fibers of natural origin may be advantageously chosen, alone or as a mixture, from the group comprising animal and/or plant fibers, for example cotton, wool, silk, flax, cellulose, and the like. By way of example, depending on the textile fiber used in the sheath, good heat resistance is obtained. If the sheath is made of wool, a good heat withstand capability is obtained.

In a second case and advantageously, the synthetic fibers can be chosen, alone or as a mixture, from the group comprising acrylics, polyamides, polypropylenes, and the like. The yarn according to the present invention will be able to withstand dyeing, printing and thermosetting, under the same treatment conditions as conventional textiles. Thus, if the yarn in a specific embodiment is made up of an outer layer of cotton, the latter may be bleached, dyed or printed under the same chemical conditions as a yarn of pure cotton.

The sheath can be preferably made by a process of assembly, wrapping, lapping, twisting, throwing, Dref™ friction spinning (from the company Fehrer AG), and the like. The mechanical implementation of the textile sheath by textile fibers, which may be short or long, by a staple fiber yarn, by a card tape, by a comb-shaped tape, which may be monofilament or multifilament, continuous or discontinuous, makes it possible to preserve the “textile handle” of the yarn. In another embodiment, all or part of the core can be covered with a porous coating so as to facilitate the attachment of the textile fiber(s) of the sheath.

In a second aspect of the present invention, a textile is characterized in that it comprises at least one composite yarn as described above. The textile can be produced by a weaving, knitting, braiding, embroidery, napping or nonwoven (by needle-punching) process, and the like. The fineness of the cross section of the strand(s) making up the core allows the composite yarn to keep its flexibility. The fineness of the cross section limits the “shape memory” phenomenon associated with the metallic yarn with a larger cross section (spring effect). The yarn of the present invention will withstand the shaping stresses specific to the use of textiles, such as shrinkage, passage of the needle, sewing machine tension, etc. The textile is pleasant to wear and will not cause the wearer any problems due to contact or, in the case of wrapping, will not cause the transported or packaged material any problems due to contact.

According to a third aspect of the invention, an article of clothing is characterized in that it is assembled using at least one composite yarn as described above.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be clearly understood and its various advantages and characteristics will emerge more clearly from the following description of the nonlimiting exemplary embodiments, with reference to the attached schematic drawings in which:

FIG. 1 represents a round core (strand) of a composite yarn according to a first embodiment;

FIG. 2 represents a side view of a first process for treating the core of FIG. 1 in order to obtain a flat core (strip) and a composite yarn according to a second embodiment;

FIG. 3 represents a side view of a second process for treating the core of FIG. 1 in order to obtain a core and a composite yarn according to a third embodiment;

FIG. 4 represents a view from above of a third process for treating the core of FIG. 2 in order to obtain a core and a composite yarn according to a fourth embodiment;

FIG. 5 represents a view from above of a fourth process for treating the core of FIG. 2 in order to obtain a core and a composite yarn according to a fourth embodiment;

FIG. 6 represents a side view of a composite yarn according to a first exemplary embodiment; and

FIG. 7 represents a view in cross section of a composite yarn according to a second exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1 and 2, and in a preferred embodiment, the core (1) of a composite yarn consists of a strand or monofilament, i.e. of a continuous round yarn, of copper (2) covered with a fine layer of silver or of tin (3). The copper yarn (2) has a diameter of approximately 67 μm. The layer of silver (3) has a thickness of approximately 5 one thousandths of the copper.

As is represented in FIG. 2, the core (1) is rolled by passing it between two rollers (4 and 6) of a smooth cold-rolling mill. A new continuous rolled core (7) of silver-plated or tinned copper, approximately 5 μm thick and with a width approximately equal to 0.20 mm, is obtained.

FIG. 3 shows a process for treating the surface of the core (1) of FIG. 1 with two knurling cylinders (8 and 9). The core of silver-plated copper yarn obtained (11) is marked in order to improve the attachment of textile yarns and/or fibers and to optimize the mass/area ratio of the metals.

FIG. 4 shows a process for treating the surface of the core (7) of FIG. 2 with two simple knurling rolls (12). The strip (13), forming the core, has transverse striations parallel to one another.

FIG. 5 shows a process for treating the surface of the core (7) of FIG. 2 with two cross knurling rolls (14). The strip (16), forming the core, has striations in staggered rows due to cross knurling.

In a first example of realization (see FIG. 6), the core in the shape of a strip (16), for example that obtained and shown according to the process of FIG. 5, is covered with a continuous textile fiber (17) by throwing or wrapping. The composite yarn obtained (18) is thus wrapped. For example, the core (16) is wrapped with a cotton of 28 metric number. Wrapping consists in covering a core yarn with one or more sheaths consisting of different yarns. The monofilament strip (16) is placed under tension in order to be wrapped with a single or double sheath. In the specific embodiment, the cotton of the first winding provides its solidity and its softness. In the case of a double wrapping, there may be an outer winding. The wrapping fiber (17) is chosen according to its characteristics, so that it provides its own qualities (heat regulation, textured fiber, etc).

In a second example of realization (FIG. 7), the core in the shape of a strip (16), for example that obtained and shown according to the process of FIG. 5, is covered with discontinuous fibers (19). The composite yarn (21) is thus obtained according to the Dref™ friction spinning technique.

Tests Carried Out with the Composite Yarns According to the Invention

The antibacterial and antifungal properties of various yarns (see Table 1 below), made up of metallic monofilaments (silver and copper) wrapped with cotton fiber, were evaluated. The yarns are converted into knits in order to be tested according to the standardized microbiological tests, according to:

Swiss standard SNV 195 920, a qualitative test which determines the antibacterial activity by diffusion on agar; this standard demonstrates the antibacterial activity of a textile support which has undergone a finishing treatment or contains a treated fiber in the mass, and which gives rise to diffusion of the active ingredient in the nutritive medium;

Swiss standard SNV 195 921, a qualitative test which determines the antifungal activity by diffusion on agar; this standard demonstrates the antifungal activity of a textile support which has undergone a finishing treatment or contains a treated fiber in the mass, and which gives rise to diffusion of the active ingredient in the nutritive medium;

French standard XP G 39-010, a quantitative test which measures the bacteriostatic properties by contact on agar; this standard makes it possible to determine the bacteriostatic activity at the surface of fabrics and polymeric surfaces acting by contact or by diffusion of the antibacterial active agent, irrespective of whether the fabrics are hydrophilic or hydrophobic; and

the French standard under preparation, a quantitative test which measures the fungistatic properties by contact on agar.

The control knit, in order to validate the microbiological assays and calculate the bacteriostatic and fungistatic effectiveness, is made from a 100% cotton yarn.

TABLE 1 Knit Nature of the yarn Silver Copper Cotton No. 1 round yarn 40% 0% 60% No. 2 round yarn  0% 40%  60% No. 3 round yarn 20% 20%  60% No. 4 flat yarn or strip 40% 0% 60% No. 5 round yarn  0% 40% tinned 60% copper No. 7 yarn with a copper partially coated low % rectangular cross with silver section Cotton  0% 0% 100%  control

The knits are vapor-sterilized before any microbiological test. Before the microbiological tests are carried out, a part of the knit test pieces is washed 10 times at 40° C., according to standard ISO 6330, in the presence of ECE laundry detergent at 3 g/l, and cold-rinsed. Table 2 indicates the results of the microbiological tests obtained using the qualitative standards SNV 195 920 and SNV 195 921. Table 3 indicates the results of the microbiological tests obtained using the quantitative standard XP G 39-010, for the various knit samples and the various strains, before and after the 10 washes at 40° C.

The strains used for the tests are Staphylococcus aureus (Gram⁺), strain present on the skin and responsible for infection, Candida albicans (yeast), strain responsible for mucosal infection, and Aspergillus niger (fungus), commonplace strain present in the environment.

TABLE 2 Standard SNV 195 920 SNV 195 921 SNV 195 921 Microorganism Staphylococcus Candida Aspergillus aureus albicans niger Knit No. 1 Knit No. 2 Knit No. 3 Weak activity Weak activity Activity Absence of Absence of Absence of inhibition zone inhibition zone inhibition zone Cotton control No activity No activity No activity Absence of Absence of Absence of inhibition zone inhibition zone inhibition zone

According to the results indicated in the table above, corresponding to the qualitative tests, and within the meaning of the standards used, the absence of an inhibition zone signifies weak activity. In reality, the absence of an inhibition zone signifies a low release of metal ions into the agar. In first approximation, a low release of metal ions into the agar heralds a weak diffusion of the metal ions to the surface which will be in contact during use (the skin in the case of an undergarment, a food product in the case of a packaging, etc). This weak diffusion heralds good biocompatibility.

The bacterial concentrations are expressed as CFU (colony forming units), as log of CFU or as difference in log of CFU (values which appear in Table 3 below), for a contact time of 24 hours. The concentrations of fungal or yeast cells are expressed as CFU (colony forming units), as log of CFU, or as difference in log of CFU (values which appear in Table 3 below), for two contact times of 24 hours and 7 days.

TABLE 3 Microorganism Staphylococcus Aspergillus Candida aureus niger albicans 10 10 10 Sample washes washes washes Knit No. 1 3.26 Knit No. 2 2.89 Knit No. 3 3.36 Knit No. 4 0.08 1.34 2.27-2.09 2.10 1.58 2.27 Knit No. 5 0.05-0.32- 1.13 1.53 Knit No. 7 1.18 1.90 Cotton 3.90 3.62 2.68-2.26 2.68 2.47 2.47 control

Under the experimental conditions, knit No. 3, which is made up of 20% of copper and 20% of silver by mass, exhibits a fungistatic activity on Aspergillus niger (qualitative tests).

Knit No. 4 (containing 40% of silver) and knit No. 5 (containing 40% tinned copper) have a bacteriostatic activity on Staphylococcus aureus before washing and after 10 washes at 40° C. This activity is due to the presence of metal in the knit:

presence of silver on the flat yarn (strip),

presence of copper and of tin at the surface of the round yarn.

Knit No. 7 (based on silver and copper) has a fungistatic activity on Aspergillus niger before washing. This activity is due to the presence of a mixture of copper and silver in the yarn with a rectangular cross section which constitutes the knit.

The yarns which constitute knits Nos. 4, 5 and 7 therefore have a bacteriostatic and/or fungistatic activity with respect to the same strains, respectively.

A flat yarn. (or strip: knit 4) is more active than a round yarn (knit 1) with respect to Staphylococcus aureus due to its structure. The round tinned copper yarn (knit 5) is more active than the other round yarns (knit 2) with respect to Staphylococcus aureus, because of the presence of tin at the surface due to the tin-plating.

The present invention is not limited to the embodiments described and illustrated. Many modifications can be made, without however departing from the context defined by the scope of the set of claims.

The uses of the yarn and of the textile according to the invention are extremely varied. By way of example, mention will be made of coiling of yarn in cartridges for swimming pool filters or air conditioning filters, yarn for assembling textiles, leathers for shoes, fabrics for furniture, mattresses, towels, clothes, food packagings, geotextiles for agriculture, horticulture, viticulture, and the like. 

1. A composite yarn, comprising a core (16) and a sheath (17, 19), characterized in that the core (16) is made from at least one yarn of one or more metallic materials with biocidal properties and in that the sheath (17, 19) is made from one or more textile fibers directly covering all or part of the core (16).
 2. The yarn as claimed in claim 1, characterized in that the yarn(s) of the core (17) is (are) made with one or more metallic materials with biocidal properties.
 3. The yarn as claimed in claim 1, characterized in that the core (16) can have an apparent surface with a structure which forms points of attachment for the textile fiber(s) of the sheath (17, 19).
 4. The yarn as claimed in claim 1, characterized in that the metallic material(s) with biocidal properties is (are) chosen, alone or as an alloy, from the group comprising zinc, silver, tin, copper, gold and nickel.
 5. The yarn as claimed in claim 1, characterized in that the textile fiber(s) of the sheath (17, 19) is (are) chosen, alone or as a mixture, from the group comprising fibers of natural origin, preferably cotton, wool, silk, flax or cellulose, artificial fibers and synthetic fibers, preferably acrylics, polyamides or polypropylenes.
 6. The yarn as claimed in claim 1, characterized in that the sheath (17, 19) is produced by a process of mechanical textile binding, spinning, throwing, wrapping, lapping, twisting or Dref™ friction spinning.
 7. The yarn as claimed in claim 1, characterized in that all or part of the core is covered with a porous coating so as to facilitate the attachment of the textile fiber(s) of the sheath.
 8. A textile, characterized in that it comprises at least one composite yarn (18, 21) according to claim
 1. 9. The textile as claimed in claim 8, characterized in that it is produced by a weaving, knitting, braiding, embroidery, napping or nonwoven process.
 10. An article of clothing, characterized in that it is assembled using at least one composite yarn (18, 21) as claimed in claim
 1. 11. The yarn as claimed in claim 2, characterized in that the core (16) can have an apparent surface with a structure which forms points of attachment for the textile fiber(s) of the sheath (17, 19). 